(CNN)-- There's a fascinating new parenting study out that caught our eye at The Chart. It involves the sleep habits of babies and toddlers.

Research suggests if mom is depressed, she's more likely to wake her baby up in the middle of the night, even if the baby is fine. Experts say if that happens occasionally, it's not a problem.

But if it happens often, it can lead to developmental issues.

In the study, published in the journal Child Development, researchers at Pennsylvania State University observed 45 families over the course of a week. The children ranged in age from 1 month to 2 years. Moms were asked questions about a variety of issues from how they were doing emotionally to the baby's sleep patterns.

Cameras were also installed to watch how the moms interacted with their babies in the middle of the night.

Here's what they found: Moms who had higher levels of symptoms of depression were more likely to respond to minor sounds, wake their baby up and nurse them (even if they weren't hungry) or pick their sleeping child up and put them in bed with them. It can be a vicious cycle.

"The more sleep you lose, the more likely you are to feel depressed," says lead author Douglas M. Teti, a professor of human development, psychology and pediatrics at Pennsylvania State University.

Related story: Marital strife affects toddlers' sleep

But before you blame the moms, Teti is quick to point out there are many other things at play, including family dynamics.

"What happens at night with the baby is a function of other things," he says. Martial strife may be one of the issues. If things aren't great with dad, "moms may want the contact comfort and the emotional security," says Teti.

But for that comfort and security, other things may be sacrificed.

Studies have found children who consistently don't get a good night's sleep have a harder time regulating their emotions. (Makes sense. As any parent will tell you, there are few things worse than a cranky toddler.)

And moms (and dads for that matter) who don't get a good night's rest may be less sensitive to their child's needs and they may not set proper limits. (Raise your hand if you've ever let your child watch an extra half hour of TV so you can crash on the couch.)

A consistent lack of sleep can make it hard for kids to bond with their parents - and the wider world.

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